Merge pull request #198 from est31/master
Partial revert of the float conversion refactor in #192
This commit is contained in:
Alex Crichton
GitHub
commit
0b9844764e
@ -1,87 +1,83 @@
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use float::Float;
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use int::{Int, CastInto};
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use int::Int;
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fn int_to_float<I: Int, F: Float>(i: I) -> F where
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F::Int: CastInto<u32>,
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F::Int: CastInto<I>,
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I::UnsignedInt: CastInto<F::Int>,
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u32: CastInto<F::Int>,
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{
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if i == I::ZERO {
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return F::ZERO;
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}
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macro_rules! int_to_float {
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($i:expr, $ity:ty, $fty:ty) => ({
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let i = $i;
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if i == 0 {
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return 0.0
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}
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let two = I::UnsignedInt::ONE + I::UnsignedInt::ONE;
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let four = two + two;
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let mant_dig = F::SIGNIFICAND_BITS + 1;
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let exponent_bias = F::EXPONENT_BIAS;
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let mant_dig = <$fty>::SIGNIFICAND_BITS + 1;
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let exponent_bias = <$fty>::EXPONENT_BIAS;
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let n = I::BITS;
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let (s, a) = i.extract_sign();
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let mut a = a;
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let n = <$ity>::BITS;
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let (s, a) = i.extract_sign();
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let mut a = a;
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// number of significant digits
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let sd = n - a.leading_zeros();
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// number of significant digits
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let sd = n - a.leading_zeros();
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// exponent
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let mut e = sd - 1;
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// exponent
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let mut e = sd - 1;
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if I::BITS < mant_dig {
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return F::from_parts(s,
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(e + exponent_bias).cast(),
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a.cast() << (mant_dig - e - 1));
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}
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if <$ity>::BITS < mant_dig {
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return <$fty>::from_parts(s,
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(e + exponent_bias) as <$fty as Float>::Int,
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(a as <$fty as Float>::Int) << (mant_dig - e - 1))
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}
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a = if sd > mant_dig {
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/* start: 0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx
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* finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR
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* 12345678901234567890123456
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* 1 = msb 1 bit
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* P = bit MANT_DIG-1 bits to the right of 1
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* Q = bit MANT_DIG bits to the right of 1
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* R = "or" of all bits to the right of Q
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*/
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let mant_dig_plus_one = mant_dig + 1;
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let mant_dig_plus_two = mant_dig + 2;
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a = if sd == mant_dig_plus_one {
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a << 1
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} else if sd == mant_dig_plus_two {
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a = if sd > mant_dig {
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/* start: 0000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQxxxxxxxxxxxxxxxxxx
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* finish: 000000000000000000000000000000000000001xxxxxxxxxxxxxxxxxxxxxxPQR
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* 12345678901234567890123456
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* 1 = msb 1 bit
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* P = bit MANT_DIG-1 bits to the right of 1
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* Q = bit MANT_DIG bits to the right of 1
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* R = "or" of all bits to the right of Q
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*/
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let mant_dig_plus_one = mant_dig + 1;
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let mant_dig_plus_two = mant_dig + 2;
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a = if sd == mant_dig_plus_one {
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a << 1
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} else if sd == mant_dig_plus_two {
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a
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} else {
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(a >> (sd - mant_dig_plus_two)) as <$ity as Int>::UnsignedInt |
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((a & <$ity as Int>::UnsignedInt::max_value()).wrapping_shl((n + mant_dig_plus_two) - sd) != 0) as <$ity as Int>::UnsignedInt
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};
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/* finish: */
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a |= ((a & 4) != 0) as <$ity as Int>::UnsignedInt; /* Or P into R */
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a += 1; /* round - this step may add a significant bit */
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a >>= 2; /* dump Q and R */
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/* a is now rounded to mant_dig or mant_dig+1 bits */
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if (a & (1 << mant_dig)) != 0 {
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a >>= 1; e += 1;
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}
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a
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/* a is now rounded to mant_dig bits */
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} else {
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(a >> (sd - mant_dig_plus_two)) |
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Int::from_bool((a & I::UnsignedInt::max_value()).wrapping_shl((n + mant_dig_plus_two) - sd) != Int::ZERO)
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a.wrapping_shl(mant_dig - sd)
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/* a is now rounded to mant_dig bits */
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};
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/* finish: */
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a |= Int::from_bool((a & four) != I::UnsignedInt::ZERO); /* Or P into R */
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a += Int::ONE; /* round - this step may add a significant bit */
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a >>= 2; /* dump Q and R */
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/* a is now rounded to mant_dig or mant_dig+1 bits */
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if (a & (I::UnsignedInt::ONE << mant_dig)) != Int::ZERO {
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a >>= 1; e += 1;
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}
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a
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/* a is now rounded to mant_dig bits */
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} else {
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a.wrapping_shl(mant_dig - sd)
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/* a is now rounded to mant_dig bits */
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};
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F::from_parts(s,
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(e + exponent_bias).cast(),
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a.cast())
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<$fty>::from_parts(s,
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(e + exponent_bias) as <$fty as Float>::Int,
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a as <$fty as Float>::Int)
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})
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}
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intrinsics! {
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#[arm_aeabi_alias = __aeabi_i2f]
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pub extern "C" fn __floatsisf(i: i32) -> f32 {
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int_to_float(i)
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int_to_float!(i, i32, f32)
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}
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#[arm_aeabi_alias = __aeabi_i2d]
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pub extern "C" fn __floatsidf(i: i32) -> f64 {
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int_to_float(i)
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int_to_float!(i, i32, f64)
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}
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#[use_c_shim_if(all(target_arch = "x86", not(target_env = "msvc")))]
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@ -92,28 +88,28 @@ intrinsics! {
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if cfg!(target_arch = "x86_64") {
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i as f64
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} else {
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int_to_float(i)
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int_to_float!(i, i64, f64)
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}
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}
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#[unadjusted_on_win64]
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pub extern "C" fn __floattisf(i: i128) -> f32 {
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int_to_float(i)
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int_to_float!(i, i128, f32)
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}
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#[unadjusted_on_win64]
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pub extern "C" fn __floattidf(i: i128) -> f64 {
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int_to_float(i)
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int_to_float!(i, i128, f64)
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}
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#[arm_aeabi_alias = __aeabi_ui2f]
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pub extern "C" fn __floatunsisf(i: u32) -> f32 {
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int_to_float(i)
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int_to_float!(i, u32, f32)
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}
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#[arm_aeabi_alias = __aeabi_ui2d]
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pub extern "C" fn __floatunsidf(i: u32) -> f64 {
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int_to_float(i)
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int_to_float!(i, u32, f64)
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}
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#[use_c_shim_if(all(not(target_env = "msvc"),
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@ -121,17 +117,17 @@ intrinsics! {
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all(not(windows), target_arch = "x86_64"))))]
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#[arm_aeabi_alias = __aeabi_ul2d]
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pub extern "C" fn __floatundidf(i: u64) -> f64 {
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int_to_float(i)
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int_to_float!(i, u64, f64)
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}
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#[unadjusted_on_win64]
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pub extern "C" fn __floatuntisf(i: u128) -> f32 {
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int_to_float(i)
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int_to_float!(i, u128, f32)
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}
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#[unadjusted_on_win64]
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pub extern "C" fn __floatuntidf(i: u128) -> f64 {
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int_to_float(i)
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int_to_float!(i, u128, f64)
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}
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}
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@ -141,116 +137,115 @@ enum Sign {
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Negative
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}
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fn float_to_int<F: Float, I: Int>(f: F) -> I where
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F::Int: CastInto<u32>,
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F::Int: CastInto<I>,
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{
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let f = f;
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let fixint_min = I::min_value();
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let fixint_max = I::max_value();
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let fixint_bits = I::BITS;
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let fixint_unsigned = fixint_min == I::ZERO;
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macro_rules! float_to_int {
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($f:expr, $fty:ty, $ity:ty) => ({
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let f = $f;
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let fixint_min = <$ity>::min_value();
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let fixint_max = <$ity>::max_value();
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let fixint_bits = <$ity>::BITS as usize;
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let fixint_unsigned = fixint_min == 0;
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let sign_bit = F::SIGN_MASK;
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let significand_bits = F::SIGNIFICAND_BITS;
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let exponent_bias = F::EXPONENT_BIAS;
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//let exponent_max = F::exponent_max() as usize;
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let sign_bit = <$fty>::SIGN_MASK;
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let significand_bits = <$fty>::SIGNIFICAND_BITS as usize;
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let exponent_bias = <$fty>::EXPONENT_BIAS as usize;
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//let exponent_max = <$fty>::exponent_max() as usize;
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// Break a into sign, exponent, significand
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let a_rep = F::repr(f);
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let a_abs = a_rep & !sign_bit;
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// Break a into sign, exponent, significand
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let a_rep = <$fty>::repr(f);
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let a_abs = a_rep & !sign_bit;
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// this is used to work around -1 not being available for unsigned
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let sign = if (a_rep & sign_bit) == F::Int::ZERO { Sign::Positive } else { Sign::Negative };
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let mut exponent: u32 = (a_abs >> significand_bits).cast();
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let significand = (a_abs & F::SIGNIFICAND_MASK) | F::IMPLICIT_BIT;
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// this is used to work around -1 not being available for unsigned
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let sign = if (a_rep & sign_bit) == 0 { Sign::Positive } else { Sign::Negative };
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let mut exponent = (a_abs >> significand_bits) as usize;
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let significand = (a_abs & <$fty>::SIGNIFICAND_MASK) | <$fty>::IMPLICIT_BIT;
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// if < 1 or unsigned & negative
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if exponent < exponent_bias ||
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fixint_unsigned && sign == Sign::Negative {
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return I::ZERO;
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}
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exponent -= exponent_bias;
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// if < 1 or unsigned & negative
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if exponent < exponent_bias ||
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fixint_unsigned && sign == Sign::Negative {
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return 0
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}
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exponent -= exponent_bias;
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// If the value is infinity, saturate.
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// If the value is too large for the integer type, 0.
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if exponent >= (if fixint_unsigned {fixint_bits} else {fixint_bits -1}) {
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return if sign == Sign::Positive {fixint_max} else {fixint_min}
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}
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// If 0 <= exponent < significand_bits, right shift to get the result.
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// Otherwise, shift left.
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// (sign - 1) will never overflow as negative signs are already returned as 0 for unsigned
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let r: I = if exponent < significand_bits {
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(significand >> (significand_bits - exponent)).cast()
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} else {
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(significand << (exponent - significand_bits)).cast()
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};
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// If the value is infinity, saturate.
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// If the value is too large for the integer type, 0.
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if exponent >= (if fixint_unsigned {fixint_bits} else {fixint_bits -1}) {
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return if sign == Sign::Positive {fixint_max} else {fixint_min}
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}
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// If 0 <= exponent < significand_bits, right shift to get the result.
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// Otherwise, shift left.
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// (sign - 1) will never overflow as negative signs are already returned as 0 for unsigned
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let r = if exponent < significand_bits {
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(significand >> (significand_bits - exponent)) as $ity
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} else {
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(significand as $ity) << (exponent - significand_bits)
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};
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if sign == Sign::Negative {
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(!r).wrapping_add(I::ONE)
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} else {
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r
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}
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if sign == Sign::Negative {
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(!r).wrapping_add(1)
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} else {
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r
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}
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})
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}
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intrinsics! {
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#[arm_aeabi_alias = __aeabi_f2iz]
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pub extern "C" fn __fixsfsi(f: f32) -> i32 {
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float_to_int(f)
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float_to_int!(f, f32, i32)
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}
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#[arm_aeabi_alias = __aeabi_f2lz]
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pub extern "C" fn __fixsfdi(f: f32) -> i64 {
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float_to_int(f)
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float_to_int!(f, f32, i64)
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}
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#[unadjusted_on_win64]
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pub extern "C" fn __fixsfti(f: f32) -> i128 {
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float_to_int(f)
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float_to_int!(f, f32, i128)
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}
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#[arm_aeabi_alias = __aeabi_d2iz]
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pub extern "C" fn __fixdfsi(f: f64) -> i32 {
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float_to_int(f)
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float_to_int!(f, f64, i32)
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}
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#[arm_aeabi_alias = __aeabi_d2lz]
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pub extern "C" fn __fixdfdi(f: f64) -> i64 {
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float_to_int(f)
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float_to_int!(f, f64, i64)
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}
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#[unadjusted_on_win64]
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pub extern "C" fn __fixdfti(f: f64) -> i128 {
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float_to_int(f)
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float_to_int!(f, f64, i128)
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}
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#[arm_aeabi_alias = __aeabi_f2uiz]
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pub extern "C" fn __fixunssfsi(f: f32) -> u32 {
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float_to_int(f)
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float_to_int!(f, f32, u32)
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}
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#[arm_aeabi_alias = __aeabi_f2ulz]
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pub extern "C" fn __fixunssfdi(f: f32) -> u64 {
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float_to_int(f)
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float_to_int!(f, f32, u64)
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}
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#[unadjusted_on_win64]
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pub extern "C" fn __fixunssfti(f: f32) -> u128 {
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float_to_int(f)
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float_to_int!(f, f32, u128)
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}
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#[arm_aeabi_alias = __aeabi_d2uiz]
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pub extern "C" fn __fixunsdfsi(f: f64) -> u32 {
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float_to_int(f)
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float_to_int!(f, f64, u32)
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}
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#[arm_aeabi_alias = __aeabi_d2ulz]
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pub extern "C" fn __fixunsdfdi(f: f64) -> u64 {
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float_to_int(f)
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float_to_int!(f, f64, u64)
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}
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#[unadjusted_on_win64]
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pub extern "C" fn __fixunsdfti(f: f64) -> u128 {
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float_to_int(f)
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float_to_int!(f, f64, u128)
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}
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}
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